The present invention relates to an apparatus for securing a toolholder within a base and more specifically relates to an adaptor for securing a quick change toolholder to a conventional base.
As an overview, metalworking operations are typically performed using a cutting insert of a hard metal. Such an insert is mounted to a toolholder. The toolholder is secured either temporarily or permanently to a base member which is part of a machine such as a lathe or a milling machine.
Because of the extreme conditions under which they operate, cutting inserts must be replaced on a regular basis. In order to do this the cutting insert must be removed from the toolholder. The economies of the metalworking operation make it inefficient to shut a machine down for the length of time required to replace a cutting insert on a toolholder. It is more desirable to utilize a removeable toolholder such that the entire toolholder with the accompanying cutting insert may be removed and replaced with another toolholder having a new cutting insert already in position on the toolholder.
With this in mind the focus for efficiency then becomes the ease and the speed with which the toolholder may be replaced. This has been one of the motivating factors producing different commercial designs for quick change toolholders.
One example of such a design may be found in U.S. Pat. No. 4,747,735 entitled "Toolholder and Method of Releasably Mounting" by Erickson et al, which is assigned to the applicant of the subject invention and which is hereby incorporated by reference.
The details of this patent, which are prior art, are shown in FIGS. 1 and 2 and will be used to provide an overview of the design for quick change toolholders.
Looking at FIG. 1, on a toolholder 10 having a forward end 15 a cutting insert 20 is mounted. The cutting insert 20 is spaced from the toolholder 10 by a shim 25, and both the cutting insert 20 and shim 25 are held to the toolholder by means such as a clamp 30 which is secured to the toolholder 10 by a pin 35. The toolholder 10 has a rearwardly facing abutment face 40 along with a tubular shank 45 extending rearwardly from the forward end 15 and has a shank wall 50. The toolholder 10 may have a slot 53 within the shank wall 50 and spaced perforations 55 in the shank wall 50. The toolholder 10 may have forwardly facing concave contact surfaces 60 within the perforations 55.
The toolholder is positioned about a longitudinal axis 56 and this axis 56 will be used as a reference throughout this specification. As evidenced by the drawings, many features discussed in the specification are symmetric about the longitudinal axis 56. For that reason, oftentimes throughout this discussion reference will be made to a single item with the understanding that such discussion will also apply to the other duplicate items.
A toolholder receiving member 65 having a forwardly facing abutment face 67 and an opening 70 along the longitudinal axis 56 is secured to a base member 75.
The base member 75 may be any of a large variety of anchors to which toolholders may be attached. One such example is the turret of a turret lathe.
Within a cylindrical passageway 80 in the base member 75 is a stub 85 which also extends into the opening 70 of the toolholder receiving member 65. A bore 90 extends longitudinally through the stub 85 and a locking rod 95 is slidably mounted within the bore 90.
Toward the forward end 97 of the locking rod 95 are depressions 100 in the rod which may be aligned with radial apertures 105 extending through the stub 85. The locking rod 95 may be moved along the longitudinal axis 56 by pulling or pushing on the locking rod base 110 which is attached to the locking rod 95. Locking elements 115 positioned within the apertures 105 of the stub 85 and within the depressions 100 of the locking rod 95 may be urged radially outwardly by moving the locking rod 95 away from the toolholder 10.
FIG. 1 shows the toolholder 10 removed from the toolholder receiving member 65. In order to secure the toolholder 10 within the toolholder receiving member 65, the locking rod 95 is positioned such that the locking elements 115 are within the depressions 100 and furthermore recessed within the radial apertures 105 such that the tubular shank 45 of the toolholder 10 may be inserted into the opening 70.
As shown in FIG. 2, with the toolholder 10 positioned within the opening 70, the locking rod 95 may be pulled in the direction of arrow 117 away from the toolholder 10 such that the locking elements 115 are displaced radially outwardly by the depressions 100 and the locking elements 115 penetrate the perforations 55 such that they contact the forwardly facing concave contact surfaces 60. When the locking rod 95 is retracted in the direction of arrow 117, the toolholder 10 is urged within the toolholder receiving member 65 and the rearwardly facing abutment face 40 of the toolholder 10 contacts the forwardly facing abutment surface 67 of the toolholder receiving member 65. This action of the locking rod 95 secures the toolholder 10 within the toolholder receiving member 65.
It should be noted in FIG. 2 that the locking elements 115 are protruding beyond the radial aperture 105 and urging the tubular shank wall 50 against the walls of the opening 70. For increased stiffness between the toolholder 10 and the toolholder receiving member 65, the locking rod 95 may be retracted further thereby causing the locking elements 115 to elastically deform a portion of the shank 45 until it contacts the walls of opening 70.
In order to provide still higher stiffness between the toolholder 10 and the toolholder receiving member 65, the tubular shank 45 may be sized relative to the opening 70 such that upon insertion of the toolholder 10 into the opening 70, there exists an interference fit and elastic deflection occurs between the shank 45 and the toolholder receiving member 65 in the vicinity of the opening 70. In such a manner the toolholder 10 may be secured to the toolholder support member 65 with a high level of accuracy and repeatability.
In order to release the toolholder 10 from the toolholder receiving member 65, the locking rod 95 is urged toward the toolholder 10 in the direction of arrow 119. In such a manner the locking elements 115 are retracted within the radial aperture 105 and adequate clearance is provided so that the toolholder 10 may be removed from the toolholder receiving member 65.
However, given elastic deformation between the shank 45 of the toolholder 10 and the toolholder receiving member 65, there may exist high frictional forces retaining the toolholder 10 within the toolholder receiving member 65. To release the toolholder 10, the locking rod 95 is extended at the forward end of the toolholder receiving member 65 such that the locking rod 95 protrudes beyond the stub 80 and contacts an impact area 120 within the tubular shank 45 of the toolholder 10. In such a manner, continued urging of the locking rod 95 toward the toolholder 10 will force the locking rod 95 against the impact area 120 thereby ejecting the toolholder 10 from the toolholder receiving member 65.
It should now be appreciated that by urging the locking rod a toolholder may be secured or released within a toolholder receiving member, and as such the device shown in FIGS. 1 and 2 provides for quick changing of a toolholder.
It should further be appreciated that the forward end 15 of the toolholder 10 is not limited to the configurations shown in FIGS. 1 and 2 and may be adapted for any number of applications. For this reason, the forward end of a toolholder similar to toolholder 10 may have a large variety of configurations to provide an entire series of toolholders 10, each with a different purpose.
A unique situation arises when an individual is interested in utilizing the variety of available toolholders but is not interested in incorporating the quick change features contained within the toolholder receiving member 65 shown in FIGS. 1 and 2. For these instances there is a need to provide a way to utilize the toolholder 10 without a need to purchase the hardware necessary to provide these quick change features.
An object of this invention is to provide a relatively inexpensive means for adapting toolholders currently utilized in quick change mechanisms for use in conventional tooling machines.
Another object of the invention is to provide a relatively simple apparatus for adapting these toolholders for mounting to a conventional machine tool.
It is a further object of this invention to provide such an apparatus with the high stiffness available in commercial quick change mechanisms.
It is still another object of this invention to provide comparable dimensional accuracy for positioning the toolholder within the toolholder receiving members to that accuracy inherent in quick change mechanisms.